A high sensitivity and high sample throughput multiple cartridge Procise Edman sequencer is requested for placement in the University of California, Davis central protein sequencing/mass spectrometry facility. Seven major users of the proposed instrument are all NIH funded investigators and who require such an Edman sequencer for protein and peptide structural characterization in their work. Areas of on-going health related research that the requested instrument can support include: general disease mechanisms and drug discovery, epitope determination in autoimmune disease, programming of epidermal keratinocyte differentiation, effects of environmental toxins on humans, protein biosynthesis mechanisms, and biochemical characterization of peptide toxins, and the basic mechanisms of transcriptional control and regulation of stress-induced gene expression. Major users wish to use the proposed instrument to determine structures of synthetic peptides from combinatorial libraries and of biological peptides isolated from complex biological mixtures, to identify proteins from SDS or 2D gels; to determine the post-translational modification sites of proteins; to identify toxin binding target proteins; to characterize unknown initiation factors from protein complexes for molecular cloning; to perform a variety of other tasks. Many of the users have NIH funded projects that will be facilitated by a highly sensitive Edman sequencer with high sample throughput.